This lets the kernel use any memory not directly used by it or the
init ramdisk. Although, now we test whether the kernel fits into
the identitymapped area. It can't really grow down there, unless it
wants to collide with user-space. Instead, modules and the like
(when they are invented), should be put in the upper memory. Or in
their own user-space process, yay, microkernel!
Jonas 'Sortie' Termansen